Audiences are categorized, so producers can easily consider who they are aiming to impress. The two main markets would be mass, and niche audiences. Mass audiences are mostly generalized to appeal to everyone or a large majority. Niche markets are smaller groups,  magazines are a good example of this as they are mostly aimed at specific demographics, such as gardening magazines are aimed at people who enjoy gardening.
A wider form of categorizing potential audiences could be by employment, which is a better method from a business perspective as These are known as categories A-E.

A- These are highly paid professionals. E.g Doctors.

B- These are moderately well paid professions. E.g Teachers.

C1- These are slightly lower class than B. E.g Managers.

C2- These are more skill based, manual professions. E.g Engineers.

D- These are unskilled, mostly manual professions. E.g Cashiers.

E- These are non-working members of society. E.g Students.